Reapply "refactor(middleware): Entferne WebApiMiddleware"

This reverts commit 381f428f77.

StaffDBServer/Program.cs

@@ -144,7 +144,6 @@ try
     app.UseDefaultFiles();
     app.UseStaticFiles();
     app.UseOpenApi();
-    app.UseDALMiddleware();
     app.UseJwtMiddleware();
     app.UseSwaggerUi(cfg => cfg.DocExpansion = "none");